How we learn that it depends in protective relaying

Protective relaying is referred to as both an art and a science. The science of protective relaying is the philosophy, basis, and guidelines used as a starting point for settings design. The art of protective relaying is the application of those rules to a system that tends not to follow the rules. Generally, only the science is taught to young engineers, leaving them frustrated until they figure out on their own that the inability of senior engineers to reply with yes or no is the art or the “it depends” part of protective relaying. Learning the concept of “it depends” can take years for young engineers. This paper illustrates the concept of it depends and emphasizes the impact it has on protective relaying. Experienced engineers will benefit from a new perspective, or at least a reminder on mentoring young engineers. Young engineers will benefit from several illustrations of the it depends concept in protective relaying.